Type I injury: characterized by injury to the AC ligaments without complete tear. The CC ligaments are uninjured. No deformity exists.
Type II injury: represents an injury to the AC ligaments with complete disruption; the CC ligaments are partially injured without a complete tear. Complete disruption of the AC ligaments leads to horizontal instability and frequently some slight radiographic asymmetry.
Type III injury: complete tears of both the CC and AC ligaments exist. Because of the horizontal and vertical instability, there will be gross deformity at the joint. The deltoid origin and trapezius are completely detached. Alternatively, the force of injury is transmitted to the coracoid and results in a fracture at the insertion of the CC ligaments.
Type IV injury: posterior separation of the ACJ exists. The force at the lateral edge of the acromion results in the anterior displacement of the acromion and the posterior displacement of the clavicle. The result is complete tears of the CC and AC ligaments and notable deformity of the posteriorly displaced clavicle.
Type V injury: a more severe type III injury. The CC and AC ligaments are completely detached, as are the fibers of the trapezius and anterior deltoid attachments, with increased displacement of the joint versus a type III.
Type VI injury: an inferior separation of the clavicle. The clavicle is displaced either below the acromion or below the coracoid. The AC ligaments are disrupted. The CC ligaments, trapezial fascia, and anterior deltoid are all likely to be injured.
Although there is some controversy with regard to clinical validation, the Rockwood classification was introduced to provide an anatomic description that guides treatment. The randomized controlled trials that have defined modern nonsurgical treatment used the older classifications of either Tossy or Allman.10 , 11 In contrast to the older classifications, the Rockwood classification further delineates the mid- to high-grade injuries and recommends surgical intervention in grades IV, V, and VI. In the previous trials, a Tossy or Allman grade III would include Rockwood types III and V, making the applicability of these classification systems questionable in high-grade injuries.9 Furthermore, type III injuries can include both stable and unstable injuries. Although these injuries are traditionally treated nonsurgically, some patients do poorly with nonsurgical management and require surgical intervention. A statement by the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine suggests the need for a IIIa and IIIb modification; the former refers to an inherently stable injury likely to be successfully treated with nonsurgical management, and the latter refers to an unstable injury likely to result in continued pain, instability, and scapular dyskinesia if treated nonsurgically.12 Currently, the most accepted classification is the Rockwood classification. However, the authors agree that stable and unstable type III injuries need to be differentiated.
Type I and II Injuries
Nonsurgical treatment has been the mainstay of treatment for type I and type II injuries.7 Evidence to support this treatment is limited, but several studies have demonstrated its efficacy. Pallis et al2 reported on 145 college athletes with low-grade (type I and type II) injuries, and only 6 patients failed nonsurgical treatment and went on to surgery. Mouhsine et al13 also examined the outcome of nonsurgical treatment for low-grade injuries and reported that half became asymptomatic with time.
Type III Injuries
The optimal treatment of type III injuries has long been the subject of debate. The review by Johansen et al11 thoroughly discusses the several prospective randomized articles, performed nearly 20 to 40 years ago, that have shown no benefit to surgical treatment because the nonsurgical cohorts had fewer complications and faster return to work. Systematic reviews, the most recent by Beitzel et al14 in 2013, have not shown significant functional outcome benefit with surgical treatment compared with nonsurgical treatment. Despite more anatomic outcomes, surgical treatment results in higher complication rates, slower return to work, and equivalent range of motion.14 Consequently, type III injuries have largely been treated nonsurgically the past few decades. However, more recent studies have described altered shoulder mechanics and scapular dyskinesia with AC separations.15 , 16
Type V Injuries
Type V injuries are treated surgically, although little evidence exists to support this treatment. The only level I or level II published data on non–surgically treated severe Tossy type III separations come from Bannister's10 randomized controlled trial. These patients had 2 cm of displacement, and, in the authors' opinion, these would be consistent with a Rockwood type V. In the nonsurgical group, four of five patients had fair or poor outcomes.10 A more recent study examined nonsurgical management of type V injuries demonstrating that most patients will return to work; however, those with >2 cm of displacement of the clavicle above the acromion were more likely to fail nonsurgical therapy.17 One other review examined type V injuries and noted that 77% of patients were able to return to work with nonsurgical management, half being manual laborers, despite modest ASES (American Shoulder and Elbow Society) and DASH (Disabilities of the Arm, Shoulder, and Hand) scores.18
Author's Preferred Nonsurgical Treatment Protocol
Multiple methods of casting and sling wear attempting to externally hold an AC reduction have been used.7 Notably, patient compliance is low, and no method has been proven to be more effective than a simple sling or shoulder immobilizer and activity modification.7 , 14 Patients undergoing nonsurgical treatment are removed from sport until symptoms resolve.
Currently, the authors do not attempt a reduction when undergoing nonsurgical treatment. Patients are treated with a sling for 2 to 3 weeks until much of the acute pain resolved, followed by therapy and early range of motion. For type I and II injuries, surgery is considered if patients remain symptomatic or unable to return to sport after 3 to 6 months of therapy and rehabilitation. Patients with a type III injury or a type V injury with <2 cm displacement and without medial-lateral instability with the clavicle not overriding acromion are brought back after 3 to 4 weeks from injury for repeat evaluation. Those who report significant improvement in pain and motion, as well as minimal scapular dyskinesia, are counseled to continue nonsurgical management. If the patients are noted to have marked scapular dysfunction and minimal improvement in pain, stability of the joint is evaluated clinically and radiographically, and surgical intervention may be offered at this point. Other considerations with regard to work demands and the ability to comply with postoperative restrictions are also taken into account in the treatment algorithm.19
More than 150 techniques for surgical treatment of AC injuries have been described.14 These techniques have generally fallen into several categories: AC fixation, CC fixation, or ligament reconstruction. On principle, acute injuries with the capacity to heal can do well with techniques that hold the reduction and allow for healing. Typically, chronic injuries require some form of biologic augmentation, most commonly with the use of a tendon graft. In the low-grade, symptomatic type I and II injuries that have failed nonsurgical treatment, an open or arthroscopic distal clavicle excision may be appropriate to provide pain relief.
AC fixation has historically involved plates, screws, or wires across the ACJ in the acute setting.7 Most commonly today, this consists of hook plates, which are secured to the clavicle with screws and span the ACJ maintaining reduction by hooking under the acromion. The plates are frequently removed approximately 3 months postoperatively. The hook plate has previously been demonstrated to result in higher outcome scores compared with nonsurgical treatment, however lower scores compared with a modified Weaver-Dunn technique.20 A more recent randomized control trial demonstrated equally good functional outcome scores between hook plate fixation and nonsurgical treatment.21
CC fixation was traditionally performed with a screw from the clavicle to the coracoid; however, modern techniques have used suspensory fixation for CC fixation in place of the rigid screw, particularly with acute injuries.22 One study compared the Bosworth screw with a suture button for treatment of acute injuries and noted no difference in maintenance of reduction, but increased patient satisfaction with the suture button.23 Fixation with one or two suture buttons as an acute repair technique has been shown to have high biomechanical stability.24 This technique is optimal for repair of acutely torn ligaments, providing stabilization to allow the native ligaments to heal.25
Modern techniques have also moved toward anatomic reconstructions using tendon grafts with or without suspensory devices used in conjunction with the graft, particularly for more chronic injuries.19 , 26 - 29 Multiple biomechanical studies have shown anatomic CC ligament reconstruction to have biomechanical properties similar to the native joint, significantly better than older techniques.30 , 31 The anatomic reconstruction was first described by Mazzocca et al32 over a decade ago. Since this description, the technique has been modified with regard to graft type, graft configuration, graft placement, fixation method, augmentation, and incorporation of graft limbs into the AC ligaments.1 , 14 , 19 , 28 , 31 - 34 As of yet, there has been no establishment of a single modification of the anatomic technique that is superior to the rest, although anatomic reconstruction seems to be preferable to nonanatomic reconstruction, given available data.14
Other Controversies in Surgical Treatments
Early versus delayed treatment continues to be a subject of debate. Few articles have compared early surgery versus delayed treatment, but the existing data trend toward improved patient satisfaction and radiographic outcomes with early treatment.35 - 37 Nevertheless, there is some difficulty drawing generalized conclusions because the available data include low-level studies with different definitions on “acute.”14 Conceptually, acute surgical treatment affords the ability to stabilize the ACJ and allows the native ligaments to heal, ideal for techniques not including biologics.25 However, the recommendation cannot be made to treat all potentially surgical ACJ separations with an acute repair, given the available data on surgical versus nonsurgical treatments. Such an algorithm would result in a potentially high number of patients undergoing surgery who would otherwise do well nonsurgically.
The counterargument is that delayed reconstruction better selects those patients who require surgery as they have failed nonsurgical management. Despite the aforementioned literature suggesting that acute repairs have better outcomes, delayed reconstructions improve outcomes from preoperative levels without subjecting patients to potentially unnecessary surgery (see Outcomes section). Delaying the reconstruction maximizes the number of patients who can be successfully treated nonsurgically.
If patients could be identified who would fail nonsurgical management, rehabilitation would be expedited if early surgery were performed. Several factors have been identified that might suggest which patients will likely fail nonsurgical management. The first is highly unstable injuries, types IV and VI specifically.7 The second is type V injuries, but specifically, if there is >2 cm displacement at the ACJ as some type V injuries can do well with nonsurgical treatment.17 , 18 Finally, dynamically unstable type III injuries will often fail nonsurgical treatment and merit consideration for surgery as recommended by International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports; these can be identified by a cross-arm AP radiograph noting the clavicle overriding the acromion or axillary radiographs with the arm abducted and adducted to evaluate for posterior displacement.12 , 19 However, these factors have not yet been prospectively validated.
Distal Clavicle Excision
Reduction of the ACJ can usually be achieved without much difficulty in the more acute setting. However, a distal clavicle excision is sometimes required to obtain reduction of chronically dislocated ACJs. Although it has been argued to retain the distal clavicle for bony stability, two recent biomechanical studies have shown that there does not appear to be a significant increase of strain on the graft with a small excision of the distal clavicle. Beitzel et al38 showed that with an intact posterior-superior AC capsule, a 5-mm resection added minimal anterior or posterior translation, but this increased with a 10-mm resection. The authors recommended maintaining the posterior-superior capsule or considering AC capsule reconstruction if needed in the setting of an AC separation.38 Beaver et al39 demonstrated no increased anterior to posterior or superior to inferior translation with biomechanical testing of a CC ligament reconstruction with and without 7 mm of distal clavicle resection.
Two studies have examined the presence or absence of distal clavicle excision as it related to early radiographic failure, but did not show any statistically significant difference between the two groups with regard to loss of reduction postoperatively.36 , 40 No other study has directly compared reconstructions with and without a distal clavicle excision with regard to functional outcome scores or revision rates. Currently, the authors' preferred approach is to attempt a closed reduction visualized with fluoroscopy after the patient is placed under anesthesia prior to prepping the shoulder. If the ACJ is unable to be reduced fully, the incision will be extended to allow for removal of the meniscal homologue or any interposed tissue and then proceed with a 5-mm distal clavicle resection with an imbrication of the capsule and possible augmentation with a limb from the graft.
Most techniques describe the use of allograft as a tendon source, but autograft has also been described.19 , 26 - 29 , 36 One study looked at allograft versus autograft as a risk factor for early radiographic failure, noting a higher failure rate in the allograft group (37.5% versus 16.7%) but was underpowered to show significance with regard to radiographic failure.36 There are no studies designed to directly comparing allograft and autograft for use in biologic augmentation in CC ligament reconstruction, and it is unknown at this time what role graft type plays in failure or loss of reduction in CC ligament reconstruction.
Author's Preferred Surgical Technique
As stated previously, most patients are given a trial of nonsurgical treatment for Rockwood types I, II, III, and V with <2 cm of ACJ displacement. Early surgical indications include Rockwood types IV, VI, and V with >2 cm of displacement or with medial-lateral instability resulting in the clavicle overriding the acromion in a high demand patient. Other surgical indications include open injuries, or injuries with neurologic deficits, or low-grade injuries (types I and II) that have failed nonsurgical therapy for 3 to 6 months. Patients with types III or V injuries who have failed nonsurgical treatment as mentioned above are also indicated for surgical intervention.
Patients with low-grade injuries and persistent pain can often be treated with a simple distal clavicle excision. Those with higher-grade injuries, symptomatic instability, or significant deformity who have failed nonsurgical management undergo arthroscopically assisted, anatomic reconstruction using biologic and synthetic fixation. As surgical intervention is rarely undertaken within the first 2 to 3 weeks from injury, the same technique is used for both subacute and chronic injuries.
The clavicle is preoperatively templated to place the conoid tunnel at 20% to 25% of the clavicular length from the distal clavicle, and the trapezoid tunnel is placed 1.5 to 2 cm lateral to this (near the anatomic insertion at 17% of clavicular length) (Figure 3). Both the tendon graft and the Dog Bone (Arthrex) are shuttled from the medial tunnel, under the coracoid, up the lateral tunnel. The ACJ is reduced and the suture button is secured, then the graft is secured on top of the clavicle. The remaining limbs may be brought over laterally to augment the AC ligament if desired (Figure 4).
Postoperative rehabilitation includes strict sling wear for 6 weeks. Motion is gradually increased after cessation of sling wear with a goal of full motion at 3 months. Strengthening begins at this point, and patients are allowed back to contact sports or combat missions in the military at 6 months.
Given the vast number of techniques described for ACJ separations, the array of complications accompanying them has also been quite large. This discussion will focus on those that are specific to recent techniques and are summarized in Table 2. Other, more infrequent complications can include adhesive capsulitis, neuropathy, distal clavicle hypertrophy, and ACJ pain.
A frequently reported complication is partial or complete loss of reduction.41 Two studies have examined the causes of failure and noted tunnel position, particularly medialization of the conoid tunnel, to be a statistically significant risk factor.36 , 40 Both studies recommend preoperatively templating tunnel position based on the clavicular length, placing the tunnels at the center of the native insertions. However, despite rates of radiographic “failure” reaching up to 53% in these military cohorts, over 82% of patients were functionally able to return to their military duties.36 , 40
Clavicle fractures have been a reported postoperative complication.26 , 33 Biomechanical studies have shown that the holes drilled for bone tunnels in the clavicle render the bone more susceptible to fracture.42 One alternative is to wrap the graft around the clavicle in lieu of placing bone tunnels. Coracoid fractures can also occur, particularly in techniques involving a coracoid tunnel.33 The graft or suture may be placed under the coracoid in a sling fashion to avoid creating a coracoid tunnel. The size of the tunnel and orientation can affect the biomechanical properties of the coracoid and risk of fracture; coracoid tunnels should be as small as possible and placed center-center from superior to inferior to minimize the risk of fracture.43 , 44 The overall rate of fracture, either coracoid or clavicle, has been calculated at 5.3% in a recent systematic review.41
Patient outcomes of anatomic reconstructions are frequently reported as highly successful (Table 3). Many of these reconstructions are chronic injuries. However, even in a military population, return to full duty in service has been reported in over 82%.36 , 40 Acute repairs have also reported high rates of maintenance of reduction and good patient outcomes (Table 4).41
As mentioned earlier, many studies have examined acute reconstruction or repair for type III injuries versus nonsurgical treatment and have not found significant differences in outcome measures.11 , 14 A more recent study, including types III, IV, and V, demonstrated again no significant difference in outcome scores at 2 years between surgical intervention with a hook plate and nonsurgical management of acute injuries.21 This study, though well performed, did not describe activity levels of the patients. All patients did return to work; nonsurgical patients tended to have improved outcomes earlier, decreased chance of complications, yet had an increased chance of being dissatisfied with cosmesis.21
Nonsurgical management has been shown to result in altered shoulder mechanics and scapular dyskinesia, decreased bench press strength, and decreased intensity in sport.15 , 16 , 49 Still, there remains a paucity of data evaluating the biomechanics of shoulder motion and strength in a comparison study between a surgical and nonsurgical shoulder. Yet, although scapular dyskinesia is thought to contribute to failure of nonsurgical management, it can persist even after surgical reconstruction.50 This fact again raises the question of whether early treatment with modern reconstruction techniques can lead to better outcomes than nonsurgical treatment.
ACJ separations are common in the athletic population, yet continue to be challenging to treat. Most ACJ injuries are low or middle grade and should be treated nonsurgically. Surgical intervention is traditionally reserved only for those who fail nonsurgical treatment or those who have the most severe of injuries. However, evidence of good or better results with acute surgical intervention may lead to a change in this treatment algorithm. Currently, data have failed to show improved long-term outcomes with acute repair versus initial nonsurgical treatment. Finally, at present, there is no single superior surgical technique with quality long-term follow-up.
References printed in bold type are those published within the past 5 years.
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© 2018 by American Academy of Orthopaedic Surgeons
50. Murena L, Canton G, Vulcano E, Cherubino P: Scapular dyskinesis and SICK scapula syndrome following surgical treatment of type III acute acromioclavicular dislocations. Knee Surg Sports Traumatol Arthrosc 2013;21:1146–1150.